<!DOCTYPE html>
<html>
	<head>
		<title>Opacity</title>
		<style type="text/css">
			div {
				width: 100px;
				height: 100px;
				margin: 40px;
				display: inline-block;
				background-color: #ee3e80;}
			p {
				width: 100px;
				height: 100px;
				position: relative;
				top: 20px;
				left: 20px;
				margin: 20px;}
			p.one {				background-color: rgb(0,0,0);				opacity: 0.5;}			p.two {				background-color: rgb(0,0,0);				background-color: rgba(0,0,0,0.5);}
		</style>
	</head>
	<body>
		<div><p class="one"></p></div>
		<div><p class="two"></p></div>
	</body>
</html>